Silver halide photographic emulsions



Patented Mar. 19, 1946 SILVER HALI'DE PHOTOGBAPHIC EMULSIONS John David Kendall and Douglas James Fry. Ilford, England, assignors to Illord Limited, llford, England, a British company No Drawing. Application January 13, 1944, So-

14 Claims.

This invention relates to silver halide photographic emulsions and particularly to selatino silver chloride photographic emulsions such as are used in development papers for contact printing, 1. e. the so-called gaslight printing papers.

It is well known that the colour of developed images obtained from geiatino silver chloride development emulsions can be controlled to some extent by the addition of certain substances to the emulsion or to the developer. In the absence any special additions the developed images may vary from a greenish to a fairly neutral black. It is generally preferred that the developed images should be on the bluer side of neutral black rather than on the greener side, and various suggestions have hitherto been made for obtaining the desired blue-black images. Thus it is known to include in the emulsion a small quantity of a quinine salt, which has the efl'ect of yielding developed images of a good blue -black colour. Various other substances have been suggested as emulsion additions for the same purpose, but none of those hitherto proposed is so satisfactory as .the quinine salts. Many compounds have likewise been suggested is developer additions, but from both manufacturers and users standpoints, it is better to include the blueblack toning substance in the emulsion since the products can then be developed with standard developers.

According to the present invention silver chloride emulsions which yield images of excellent blue-black colour on development are obtained by including in the emulsion, during its manufacture, a quinoline compound of the general formula:

8 gr Rz where R1 is an alkyl or aralkyl group, R2 is a hydrogen atom or an alkyl or aralkyl group, or R1 and R2 together form the residue of an alicyclic nucleus, and R: is a hydrogen atom or a lower alkyl group. These compounds may be further substituted in the carbocyclic ring and may be applied in the form of their mineral acid salts.

Thus the compounds employed are essentially i-alkyl quinolines or 4-aralkyl quinolines which may or may not contain other substituent groups. It is found that any substituents may be present in the carbocyclic ring, e. g. halogen atoms, hydrocarbon groups or alkoxy, aryloxy or aralkyloxy groups, or benz groups fused to the carbocyciic ring, though lower alkyl substituents and lower alkoxy substituents are preferred. Compounds containing benz groups fused to the carbocyclic ring, e. g. in the 5:6- or 7:8-positions.

rialsNo. 518,106. In Great Britain February 12,

lower alkyl group are less efiective for the purposes of this invention than the corresponding compounds in which the 2-position is unsubstituted; for example, 2:4-dlmethyl quinoline, though efi'ective, is considerably less effective than i-methyl quinoline.

Specific compounds which are of particular value are i-methyl quinoline containing no other substituent roup, and 4-methyl quinollnes containing the following additional substituent groups: 3methyl, 3-ethy1, G-methyl, l-methyl, 6- methoxy, fi-ethoxy, B-ethoxy, and combinations of such groups. Other compounds of particular value are the corresponding compounds where the 4-methyl group is replaced by a 4-ethyl, i-higher alkyl or 4-benzyl group. Particularly valuable compounds of the type where R1 and R1 in the formula form an alicyclic ring are 3:4-tetramethylene quinoline and corresponding compounds containing alkyl or alkoxy groups in the carbocyclic ring oi the quinoline nucleus.

[As indicated above, the compounds can be used either as the free bases or as mineral acid salts. Thus, for example, the compounds may be used as the hydrochlorides or bisulphates.

The proportion of compound added to the emulsion will depend on the particular compound used and on the precise nature of the emulsion. In general a good blue-black tone can be obtained using the compounds of this invention in proportions oi the order of 25 cos. of a 1% solution of the compound per pound of emulsion, though -lower proportions or higher proportions can be used, e. g. of the order of 5 to 50 cos. of a 1% solution per pound of emulsion.

Many substances when added to photographic emulsions have undesirable effects on the qualities of an emulsion, i. e. loss of speed, increased tendency to the formation of fog (i. e. developed silver not arising from the exposure) and on the contrast of the developed images. It is a particular merit of the compounds used as blue-black toners according to the present invention that they do not have any serious adverse efi'ect in respect of any of these properties.

The following examples illustrate the invention:

' Examples A gelatino silver chloride emulsion of the "gaslight" type was prepared and to portions of it were added proportions of different compounds according to this invention. A control sample containing quinine bisulphate as the blue-black toning agent was also prepared. The quinine bisulphate and other compounds were each added in the proportion of 25 cos. of a 1% solution per pound of emulsion. The samples were coated on paper base, exposed, developed in a standard metol-hydroquinone developer, and the photographic properties of the images obtained were studied. The image colours compared with the quinine control were as follows:

Example No. Compound Image colour qitllnllne con- Quinine bisulphate Standard blue.

ro i l i-mcthylquinoline Shade less blue than standard. 2 6-etho1y-4-methyl qulnoline Similar to standhydrcchloride. ard. 3 6-rnethoxy-4-metl1ylquinollne Bluer than standhydrochloride. ard. 4 4:6-dimethylquinoline hydro- Slightlybluer than chloride. standard. 5 S-ethoxy-i-methyl qulnoline Shade bluer than hydrochloride. standard. 6 3:4-dimethyl-quinoline hydro- Distincily blucr chloride. than standard. 'i' dethoxy-fiA-dimethyl quino- Trace less blue line bisulphate. than standard. 8 4:7-dimethyl quinoline hydro- Slightly hluer than chloride. standard. 9 3:4-dimethyl quinoline bisul- Distinctly bluer phate. than standard. l0 Mthyl-i-methylquinolinehy- Similar to standdrochloride. ard but slaty blue. 11. 3:4-tetrarnethylene qulnoiine Do.

bisulphate.

The solutions of the compounds of the examples were made in ethyl alcohol or water according to convenience. It will be noted that all of the compounds effect a very substantial blueing of the image colour, always comparable with that obtained by the use of quinine, and in some cases even greater than that obtained by the use of quinine. Moreover, the speed loss resultant on the use of the compounds was in no case very serious, and in most cases was not very much diflerent from the speed loss resultant on the use of quinine.

The compounds did not lead to any substantial increase in the fog level of the emulsion, and did not afiect the contrast characteristics of the emulsion to any marked extent. All the compounds therefore are very valuable substitutes for quinine.

It is to be understood that in the foregoing description and in the following claims the expression "silver chloride photographic emulsion means a photographic emulsion in which the predominant silver salt is silver chloride and includes the possibility of a small proportion of other silver halide being present.

What we claim is:

l. Silver-chloride photographic emulsions containing a compound selected from the class consisting of compounds of the general formula:

where R1 is selected from the class consisting of alkyl, aralkyl and, with R2 and the two carbon atoms of the heterocyclic ring attached thereto. an alicyclic nucleus; R2 is selected from the group consisting of hydrogen, alkyl, aralkyl, and, with R1 and the two carbon atoms or the hcterocyclic ring attached thereto, an allcyclic nucleus; R3 is selected from the group consisting of the hydrogen atom and lower' alkyl groups; R is a member of the group consisting of the hydrogen atom. halogen atoms, hydrocarbon, alkoxy, araloxy, aralkyloxy and a hydrocarbon radical which forms a benzene ring with two adjacent carbon atoms of the carbocyciic ring; and the mineral acid salts of any such compounds.

2. .A photographic element comprising a support bearing a gelatino silver chloride emulsion layer containing a compound selected from the class consisitng 01' compounds of the general formula where R1 is selected from the class consisting of alkyl, aralkyl, and. with R: and the two carbon atoms oi the heterocyclic ring attached thereto, an alicyclic nucleus; R2 is selected from the group consisting of hydrogen, alkyl, aralkyl and, with R1 and the two carbon atoms of the heterocyclic ring attached thereto, an alicyclic nucleus; Ra is selected from the group consisting of the hydrogen ato'm and lower alkyl groups; R4 is a member of the group consisting or the hydrog atom, halogen atoms, hydrocarbon, alkoxy. aryloxy, aralkyloxy and a hydrocarbon radical which forms a benzene ring with two adjacent carbon atoms of the carbocyclic ring: and the mineral acid salts of any of such compounds in an amount of the order of 5-50 cos. of a 1% ethyl alcohol solution per pound of emulsion.

3. Gelatino silver chloride photographic emulsions containing a 4-alkyl quinoline which is unsubstituted in the 2-position and in which the group attached to the carbon atom in the 3-position is selected from the class consisting of the hydrogen atom and alkyl and aralkyl groups.

4. Gelatino silver chloride photographic emulsions containing a ll-methyl quinoline which is unsubstituted in the 2-position and in which the group attached to the carbon atom in the 3-position is selected from the class consisting of the hydrogen atom and alkyl and aralkyl groups.

5. Gelatino silver chloride photographic emulsions containing a i-alkyl quinoline which is unsubstituted in the 2-position and which contains an alkoxy substituent in the carbocyclic ring and in which the group attached to the carbon atom in the 3-position is selected from the class consisting of the hydrogen atom and alkyl and aralkyl groups.

6. Gelatino silver chloride photographic emulsions containing a e-methyl quinoline which is unsubstituted in the 2-position and contains a lower alkoxy substituent in one of the 6 and 8 positions and in which the group attached to the carbon atom in the 3-position is selected from the class consisting of the hydrogen atom and alkyl and aralkyl groups.

7. Gelatino silver chloride photographic emuL- sions containing a 4-alkyl quinoline which is unsubstituted in the 2-position and contains a lower alkyl substituent in the 3-position.

8. Gelatino silver chloride photographic emulsions containing a d-methyl quinoline which is unsubstituted in the 2-position and contains a lower alkoxy substituent in one of the 6 and 8 positions and a lower alkyl substituent in the 3- position.

9. Gelatino silver chloride photographic emulsions containing a mineral acid salt of a i-alkyl quinoline which is unsubstituted in the Z-position and in which the group attached to the carbon atom in the 3-posltion is selected from the class consisting'of the hydrogen atom and alkyl and aralkyl groups. r

10. Gelatino silver chloride photographic emulsions containing a mineral acid salt of a i-alkyl quinoline which is unsubstituted in the 2-p0sition and contains a lower alkoxy substituent in one of the 6 and 8 positions and in which the group attached to the carbon atom in the 3-position is selected from the class consisting of the hydrogen atom and alkyl and aralkyl groups.

11. Gelatino silver chloride photographic emulsions containing a mineral acid salt of a 4-a1kyl quinoline which is unsubstituted in the 2-position and contains a lower alkyl substituent in the 3-position.

12. A photographic element comprising a support hearing at least one gelatino silver chloride emulsion layer which layer contains a i-methyl quinoline which is unsubstituted in the fl-position and in which the group attached to the carhon atom in the 3-position is selected from the class consisting oi the hydrogen atom and alkyl and aralkyl groups.

13. A photographic element comprising a sup port hearing at least one gelatino-silver chloride emulsion layer which layer contains a small amount of G-methoxy-i-metlwl-quinoline hydrochloride.

14. A photographic element comprising a sup-'- port hearing at least one selatino-silver chloride emulsion layer which layer contains a small amount 01' 3,-i-dimethyl quinoline hydrochloride.

Jorm navm KENDALL. DOUGLAS JAMES FRY.

Certificate oi Correction Patent No. 2,397,015.

numbered patent March 19, 1946.

JOHN DAVID KENDALL ET AL.

It is hereby certified that errors appear in the requu'ing correction as follows:

grinted specification ofs the above age 2, first column, line 8, for

emulsion read emulsion; and second column, line 13, for consisitng read consisting;

line 55, for cox-b on read carbon; page 3, second col ztfoups and before the period insert tn an amount of yl alcohol sobutton pcr pound of emulsion; and that that the same may conform to the record of the read with these corrections therein case in the Patent Oflice.

umn, line 8, claini 12, after the order of 5-50 cos. of a I? the said Letters Patent should a Signed and sealed this 28th day of May, A. D. 1946.

ilw-l LESLIE FRAZER,

M'Aniaionl C'ommiuiomr of Patents.

9. Gelatino silver chloride photographic emulsions containing a mineral acid salt of a i-alkyl quinoline which is unsubstituted in the Z-position and in which the group attached to the carbon atom in the 3-posltion is selected from the class consisting'of the hydrogen atom and alkyl and aralkyl groups. r

10. Gelatino silver chloride photographic emulsions containing a mineral acid salt of a i-alkyl quinoline which is unsubstituted in the 2-p0sition and contains a lower alkoxy substituent in one of the 6 and 8 positions and in which the group attached to the carbon atom in the 3-position is selected from the class consisting of the hydrogen atom and alkyl and aralkyl groups.

11. Gelatino silver chloride photographic emulsions containing a mineral acid salt of a 4-a1kyl quinoline which is unsubstituted in the 2-position and contains a lower alkyl substituent in the 3-position.

12. A photographic element comprising a support hearing at least one gelatino silver chloride emulsion layer which layer contains a i-methyl quinoline which is unsubstituted in the fl-position and in which the group attached to the carhon atom in the 3-position is selected from the class consisting oi the hydrogen atom and alkyl and aralkyl groups.

13. A photographic element comprising a sup port hearing at least one gelatino-silver chloride emulsion layer which layer contains a small amount of G-methoxy-i-metlwl-quinoline hydrochloride.

14. A photographic element comprising a sup-'- port hearing at least one selatino-silver chloride emulsion layer which layer contains a small amount 01' 3,-i-dimethyl quinoline hydrochloride.

Jorm navm KENDALL. DOUGLAS JAMES FRY.

Certificate oi Correction Patent No. 2,397,015.

numbered patent March 19, 1946.

JOHN DAVID KENDALL ET AL.

It is hereby certified that errors appear in the requu'ing correction as follows:

grinted specification ofs the above age 2, first column, line 8, for

emulsion read emulsion; and second column, line 13, for consisitng read consisting;

line 55, for cox-b on read carbon; page 3, second col ztfoups and before the period insert tn an amount of yl alcohol sobutton pcr pound of emulsion; and that that the same may conform to the record of the read with these corrections therein case in the Patent Oflice.

umn, line 8, claini 12, after the order of 5-50 cos. of a I? the said Letters Patent should a Signed and sealed this 28th day of May, A. D. 1946.

ilw-l LESLIE FRAZER,

M'Aniaionl C'ommiuiomr of Patents. 

